A main function of a motor controller in a pure electric vehicle or a hybrid vehicle is to convert the direct current power provided by the high-voltage battery into three-phase alternating current power required by a motor, and drive the motor under the control of the vehicle controller, to provide driving or braking torque for the vehicle.
At present, functional safety is required for the motor controller applied to a pure electric or hybrid passenger vehicle. Generally, the motor controller with the functional safety requirement is required to enter a safety state by a shutoff path when detecting a failure against the safety goal, thereby avoiding hazards to the driver and passengers. The safety state of the motor controller generally means that the output torque of the motor controlled by the controller is approximately zero, which will not cause uncontrollable acceleration or deceleration of the vehicle. At present, there are mainly two types of safety states, namely, an active short circuit state and a bridge arms all shutoff state, which have advantages and disadvantages under conditions of low speed and high speed. A reasonable solution is to enter the bridge arms all shutoff state under condition of low speed, and enter the active short circuit state under condition of high speed. In this solution, the shutoff path of the motor controller for entering the safety state is to determine whether the motor speed is in a low speed zone or a high speed zone by collecting a motor speed signal, and then generate a shutoff state control signal according to the determination result, so as to perform the control operation to enter the bridge arms all shutoff state or the active short circuit state.
In the solution of the conventional technology, since the shutoff path is required to have a high safety level, the requirement on the failure rate of each device (a microprocessor or a logic operation circuit) involved in the above shutoff path in the motor controller is relatively high, which results in a high difficulty on designing the device.